“Every living thing on Earth has a unique set of strategies to adapt to life-threatening situations in the environment,” Dr. Zhu said at the meeting. “The surprise discovery we never expected is that most of the genes responsible for pesticide resistance in the bedbug are active in its outer skin-like shell or cuticle. This is the unique adaption that has not been discovered in cockroaches, termites, ants or other insects.”

Dr. Zhu and colleagues from the University of Kentucky determined that the location was the perfect spot for genes capable of blocking the effects of the common home and garden pesticides known as pyrethroid insecticides. Since the bodies of bedbugs are extremely flat before they consume human blood, they are perfectly adapted to hiding in the seams of mattresses, upholstery, suitcase linings and other similar locations.

However, it also creates a vulnerability to environmental toxins and gives bedbugs an abnormally large surface area through which pesticides could enter their bodies, the authors said. While the hard shell makes it difficult to squash a bedbug, according to Dr. Zhu’s team, it is also a “metabolic hot spot” when it comes to protecting against insecticides. Some of the cuticle’s genes, they note, produce substances which rip apart the molecular structure of these pest-killing substances, rendering them completely ineffective.

The researchers analyzed the bedbug’s entire genome, focusing on 21 different populations in cities located in Ohio and Kentucky. Using advanced genetic sequencing technology, they were able to locate 14 genes that in various combinations help the insects survive treatments with pyrethroid-type insecticides.

The majority of those were active in the bug’s cuticle, where it can slow down or prevent pesticides from reaching the nerve cells and killing the bedbugs, while a second line of defense helps the pests fight off the toxins before they can do any damage. Dr. Zhu said that those findings suggest that new pesticides need to be developed – pesticides that focus on chemicals that can mute the genes in the cuticle that block current insecticides.

“It reminds us how quickly a new insecticide can become ineffective,” Dr. Zhu said. “In the future, efficient bedbug management should not rely on any single insecticide. We need to combine as many chemical and non-chemical approaches as we have to get rid of the infestation.”